Feature request: Use stdbool.h or C23 predefined constants

[schwehr]

It would be nice if we could remove some of the custom defines in cpl_serv.h. First up might be FALSE/TRUE:

libgeotiff/libgeotiff/cpl_serv.h

Lines 73 to 79 in 5d5a36d

	#ifndef FALSE
	# define FALSE 0
	#endif
	#ifndef TRUE
	# define TRUE 1
	#endif

Can we assume at least C99 for libgeotiff?

• <C23 - stdbool.h - https://en.cppreference.com/w/c/types
• C23 - https://en.cppreference.com/w/c/language/bool_constant

I think we can also remove NULL:

#ifndef NULL
#define NULL 0
#endif

[rouault]

Can we assume at least C99 for libgeotiff?

yes, pretty reasonable. If you want to tackle that, you're welcome

[schwehr]

It might be a while before I get to it, but I'm definitely up for doing it.